Conventionally, for example, in automotive electrical components such as lamps and ECUs (Electrical Control Units) for automobiles, OA (Office Automation) equipment, home electric appliances, medical equipment, etc., an opening is provided in a housing for containing electronic components, a control board, etc. to reduce pressure fluctuation in the housing due to temperature change or to ventilate the housing, and a vent member is attached to this opening. This vent member not only ensures ventilation between the interior and exterior of the housing but also prevents foreign substances such as dust and water from entering the housing.
For example, Patent Literature 1 discloses a vent member 100 as shown in FIG. 8. This vent member 100 includes an overall tubular support body 110 fitted into an opening 151 of a housing 150, a waterproof gas-permeable membrane 120 that closes a vent passage which is the interior space of the support body 110, and a cover 130 that covers the waterproof gas-permeable membrane 120. The support body 110 has a base portion 111 to which the waterproof gas-permeable membrane 120 is bonded and a stem portion 111 extending from the base portion 111 so as to be engaged with the inside surface of the housing 150 through the opening 151. A seal member 140 is fitted to the base of the stem portion 112. This seal member 140 is pressed against the surface of the housing 150 by the base portion 111, and thereby a gap between the support body 110 and the housing 150 is sealed.